Hi all,
I got a 53 GMC truck with LT1 engine/4L60E transmission and PCM 16188051 out of 94 Fleetwood.
I installed an aftermarket AC system and wanted the compressor clutch to be controlled by PCM. Reason for that - proper fans and idle control, as well as compressor clutch control at certain conditions.
The problem I am having is - PCM would not command the clutch to engage.
The PCM has a bin from 94 Firebird flashed (same service number) because it has a subroutine for Performance mode.
AC request signal is wired via dash button, evaporator thermostat and low pressure switch. The rest of AC electrical part is done per Fleetwood service manual, including factory pressure sensor, clutch status signal, diode on the compressor, relay. The only thing missing is evap temperature sensor - I wired a resistor and the PCM sees 20 degrees Celsius all the time.
I deleted power steering sensor and EGR.
I attached BIN file and a zip with EEhack log file.
As I turn ignition on, PCM would test AC clutch successfully.
With engine running I press AC button, PCM sees the AC request signal, but the clutch would not engage. No codes are present.
If I command to turn AC clutch on, it will engage and AC on flag would set (not sure if that matters).
What I noticed when recording the last log is after I manually trigger AC on, then turn it off - fan1 would keep running for another 10 seconds or so and after the fan shuts off I would press AC button but PCM would not show request signal anymore until I restart the engine.
Please help - what am I missing?
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